This invention relates generally to measuring apparatus and, more particularly, is directed to apparatus for measuring facial swelling of a patient which may occur after surgical removal of wisdom teeth.
The surgical extraction of impacted wisdom teeth is followed almost invariably by some degree of post-operative swelling of the related soft tissues. Various anti-inflamatory drugs have been utilized for reducing such swelling. In order to assess the anti-inflamatory effects of these drugs, it is necessary to measure the extent that the swelling is reduced over a period of time. However, one of the major difficulties in investigations of facial swelling is that of accurately measuring the swelling. With the measuring techniques utilized to date, pre-operative and post-operative measurements are taken and the results are compared to obtain an indication of the extent of swelling.
Several measurement techniques have been employed to assess swelling following surgery, including stereophotogrammetry and contrast radiography. The stereophotogrammetric technique is disclosed in an article, D. A. Dixon et al., "Minimal Forms of the Cleft Syndrome Demonstrated by Stereophotogrammetric Surveys of the Face", British Dental Journal, Mar. 7, 1972, pgs. 183-189. In addition to the above techniques, clinical analysis, that is, observation of the patient, has also been utilized to determine the extent of swelling. William B. Linnenberg, "The Clinical Evaluation of Dexamethasone in Oral Surgery", Oral Surgery, Oral Medicine and Oral Pathology, Vol. 20, No. 1, 1965, pgs. 6-28.
Still further, mechanical techniques for measurement of swelling have been utilized. For example, with one mechanical method, one arm of a pair of callipers is placed in the interdental space between the mandibular first and second molars and the other arm of the callipers is placed in light contact with the external cheek surface. J. H. Sowray, "An Assessment of the Value of Lyophilised Chymotrypsin in the Reduction of Post-Operative Swelling Following the Removal of Impacted Wisdom Teeth", British Dental Journal, Feb. 21, 1961, pgs. 130-133. However, utilization of callipers does not provide an accurate measurement of the extent of swelling since such measurement is taken at a single point on the cheek. A similar mechanical technique is desribed in the article "An Investigation into Some of the Factors Concerned in the Surgical Removal of the Impacted Lower Wisdom Tooth, including a Double-Blind Trial of Chymoral", by Ian W. Cameron, published in the British Journal of Oral Surgery (1980) 18, pgs. 112-124. However, as recognized on page 121 of this article, the device used therein is only capable of measuring the maximum lateral extension of the swelling of the cheek. It is to be noted that the latter article at page 121 indicates that a volume measurement would be a true measure of post-operative oedema, but further indicates that no such measurement seems possible unless using a very sophisticated stereophotogrammetric technique.
Another mechanical technique that has been utilized is described in the article, P. Lokken, "Bilateral Surgical Removal of Impact Lower Third Molar Teeth as a Model for Drug Evaluation: A Test for Ibuprofen", Europ. J. clin. Pharmacol. 8, pgs. 209-216, 1975. The device of this latter article consists of 16 adjustable plastic screws, eight on each side of the face, on bilateral plates, which are fixed on a facial bow attached to an individual bite-block. The plastic screws are adjusted into touching contact with the skin and are adjusted at each sitting and then compared with pre-operative measurements to give an indication of swelling. However, again, with this device, only point measurements are taken.